Violetta (and everyone else in the party) has been through an outlandish amount of mayhem and repeatedly pushed her skills to their limits since winding up in Agatha's company. She's racked up a whole lot of practical experience under extreme circumstances. She's earned her power-ups. The inspirational aura of a spark doubtless contributes -- this is important, keep doing your best work! -- but I hope that's more like motivation and dedication and less like reshaping people. The spark aura is already alarmingly mind-control-y in a story that has strong opinions about mind control.